## Team for Advanced Flow Simulation and Modeling |

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## Contaminant Dispersion in a Model Subway StationIn this simulation, the subway station has two entrances on each side and four vents at the ceiling. The air is assumed to enter the station from the left (inflow boundary) at a rate of 0.75 m/s. The air is also ventilated through each vent at a rate of 0.15 m/s. This simulation is carried out on a CRAY T3D in two stages. First, the full Navier-Stokes equations are solved to obtain the velocity field throughout the subway station. This velocity field is used in the second stage in the time-dependent contaminant dispersion equation to determine the concentration of the contaminant. Here, the contaminant is released from a point source, with constant strength, located close to the inflow boundary. The Prandtl and Lewis numbers in this computation are 0.72 and 1.0 respectively. The mesh used in the simulation consists of 187,612 nodes and 1,116,992 tetrahedral elements. The steady-state solution of the incompressible Navier-Stokes equations is obtained by solving over 0.65 million coupled, nonlinear equations at ever pseudo-time step. The transient solution of the equations governing the contaminant dispersion involves solution of a linear system with more than 0.15 million equations at every time step. The first image below shows the geometry of the subway station. The bottom images show the contaminant concentration at four instants in the simulation. The movie shows the contaminant dispersing through the subway station.
The unstructured mesh generator, flow solver, and flow visualization software (based on BoB and Wavefront) were developed by the T*AFSM. ## References: 1. T.J.R. Hughes, T.E. Tezduyar and A.N. Brooks, "Streamline Upwind
Formulations for Advection-Diffusion, Navier-Stokes, and First-order
Hyperbolic Equations", 2. T.E. Tezduyar and D.K. Ganjoo,
"Petrov-Galerkin Formulations with Weighting Functions Dependent Upon
Spatial and Temporal Discretization: Applications to Transient
Convection-Diffusion Problems", 3. T.E. Tezduyar and J. Liou, "Adaptive Implicit-Explicit Finite
Element Algorithms for Fluid Mechanics Problems", 4. T.E. Tezduyar, "Stabilized Finite Element Formulations for
Incompressible Flow Computations", 5. T. Tezduyar, S. Aliabadi, M. Behr, A. Johnson, V. Kalro and M.
Litke, "Flow Simulation and High Performance Computing", 6. T. Tezduyar, "Advanced Flow Simulation and Modeling", 7. T. Tezduyar, "CFD Methods for Three-Dimensional Computation of
Complex Flow Problems", 8. T. Tezduyar and Y. Osawa, "Methods for Parallel Computation of
Complex Flow Problems", |